Who could he have had in mind? Surely not Stephen Carter, who delights in the job title "Principal Advisor to the Prime Minister", earns a reported Â£180,000 per year, and is not regarded by colleagues as the most humble of men.

I'm told that when Carter took up his post in No10, Byrne wrote to him offering to provide advice and help. Byrne has told friends he regarded Carter's reply as "rude and dismissive", and has been smarting ever since.